Dog ecology and demography information to support the planning of rabies control in Machakos District, Kenya

A study of 150 dog-owning households from six randomly selected sublocation s was conducted in Machakos District, Kenya. Initially all households were visited to collect information on dog ecology and demography based on WHO g uidelines and to collect serum for rabies antibody detection. A second visi t was made 1 year later, to obtain follow-up data on births, deaths, dog mo vements and other events since the first visit. Dog ownership was common, w ith a range of 53-81% (mean = 63%) of households owning dogs in the six sub locations. Dog density for the five more rural sublocations ranged from 6 t o 21 dogs km (1) and for the peri-urban sublocation was 110 dogs km(-2). Th e dog population was estimated to be growing at 9% p.a. (95%:1 C.I. 4-14%). This growth was a function of very high fecundity (1.3 females per Female per year) more than compensating for high mortality particularly among fema les. Life expectancy from birth was 3.5 years for males and 2.4 years for f emales. Half the dogs at any one time were less than 1 year of age. All dog s, by design of the study, were owned. Of these, 69%;, were never restricte d and roamed freely to forage for food and mix with other dogs. Only a smal l proportion of dogs (5%) were fed commercial dog food. Most households rep orted observing dogs scavenging their garbage, including: their own dogs (8 1%), their neighbours' dogs (75%) and unknown dogs (451%). Only 29% of dogs at least 3 months of age were reported to be vaccinated against rabies. Th e proportion vaccinated varied widely between sublocations (5-68 degrees,), 48% of dogs reportedly vaccinated had detectable antibodies, 31% at or abo ve levels considered to indicate seroconversion. The proportion of dogs wit h detectable antibodies declined according to the time since last vaccinati on (55%, if vaccinated less than or equal to 1 year, 47% less than or equal to 2 years and 36% > years); 20%, of dogs reported not to have been vaccin ated had detectable rabies antibody. Compared to other dog populations in r ural eastern and southern Africa, Machakos District has a high density of d ogs. The Machakos dog population is growing, highly dynamic, poorly supervi sed and inadequately vaccinated against rabies. The main implication for ra bies control is that adequate vaccination coverage is unlikely to be achiev ed, even under optimal delivery, using the current strategy of annual vacci nation of dogs older than 3 months. (C) 2001 Elsevier Science B.V. All righ ts reserved.